Voltage-dependent calcium channels (VDCCs) play an essential role in regulating cerebral artery diameter and it is widely appreciated that the L-type VDCC, CaV1.2, encoded by the CACNA1C gene, is a principal Ca2+ entry pathway in vascular myocytes. However, electrophysiological studies using 10 mM extracellular barium ([Ba2+]o) as a charge carrier have shown that ~20% of VDCC currents in cerebr...

The studies presented here were performed to determine the effect of agonist stimulation on the cytosolic free Ca2+ concentration ([Ca2+]i) in single smooth muscle cells, freshly isolated from afferent arterioles and interlobular arteries averaging between 10 to 40 microns in diameter. Microvessels were obtained from male Sprague-Dawley rats using an iron oxide collection technique followed by ...

Extracellular concentrations of Ca2+ change rapidly and transiently in the brain during excitatory synaptic activity. To test whether such changes in Ca2+ can play a signaling role we examined the effects of rapidly lowering Ca2+ on the excitability of acutely isolated CA1 and cultured hippocampal neurons. Reducing Ca2+ excited and depolarized neurons by activating a previously undescribed nons...

The cytoplasmic free calcium ion concentration ([Ca2+]i) of cultured guinea pig ileum longitudinal muscle cells loaded with a fluorescent [Ca2+]i indicator, fura-2, was measured by digital ratio imaging microscopy. Spontaneous [Ca2+]i oscillations were observed in 25% to 80% of the cells, which differed with the batches of the cultured cells after 5 to 8 days in culture. The frequency and ampli...

Distinct spatiotemporal Ca2+ signalling events regulate fundamental aspects of eukaryotic cell physiology. Complex Ca2+ signals can be driven by release of Ca2+ from intracellular organelles that sequester Ca2+ such as the ER (endoplasmic reticulum) or through the opening of Ca2+-permeable channels in the plasma membrane and influx of extracellular Ca2+. Late endocytic pathway compartments incl...

BACKGROUND Troglitazone (TRO), a novel antidiabetic drug, has been reported to decrease blood pressure and relax vascular strips. The mechanism of relaxation induced by TRO was determined in terms of Ca2+ signaling in smooth muscle cells. METHODS AND RESULTS Front-surface fluorometry and fura 2-loaded medial strips of porcine coronary artery were used to examine the effects of TRO on cytosoli...

Tension development in arterial smooth muscle is regulated by variations of calcium concentration in the submicromolar range. The receptor for Ca2+ is calmodulin, which through stimulation of myosin light chain kinase can activate sequentially two apparently different contractile states. A third possible contractile state may be related to C-kinase activation. These contractile states are thoug...

Interleukin-8 (IL-8) plays an important role in the activation of neutrophil granulocytes. Although intracellular Ca2+ signals are essential in this process, they have not been studied in great detail so far. Here, we have measured IL-8-induced Ca2+ signals in single human neutrophil granulocytes using the Ca2+ indicator dye FURA-2 AM and we have investigated the signal transduction that leads ...

Recently we showed that staurosporine uses the extracellular calcium ions to affect on neurite outgrowth in PC12 cells. However, these mechanisms during staurosporine-induced cell death are still unclear. In this study, we investigated the relation between of reactive oxygen species (ROS) and extracellular calcium entry during staurosporine-induced cell death in PC12 cells. The results showed t...

Platelets maintain a low cytosolic free Ca2+ concentration by limiting Ca2+ influx from plasma and promoting Ca2+ efflux. The present studies examine the role of the plasma membrane Na+ gradient in these processes. The Na+ gradient in intact unstimulated platelets was altered by incubating the platelets with ouabain or by replacing extracellular Na+ with N-methyl-D-glucamine or choline. Ca2+ fl...